MyHeritage seems to use a member's username rather his/her real name when displaying his/her actions on email updates. For instance, email updates will say "Andre965 did this and that", rather than "André Levy did this and that".
I had the same issue Andre. It's easy to fix though. SImply go to your profile page and change your name to what you would like it to appear as in emails, etc. Your full name will still appear as per normal in your 'tree' so don't worry about that.
Thanks, Janine. Apologies for being daft, but I couldn't find the username field in my profile.
As a simple product improvement recommendation, I'd suggest MyHeritage should minimise the amount of similar fields it uses. For instance, there is a name that is used in the tree, another one in the profile, and yet another one as a username. That's bound to generate confusion.